Lubricated part having partial hard coating allowing reduced amounts of antiwear additive

ABSTRACT

A lubricated part composition containing (a) a part with at least a partial hard surface coating of average thickness less than about 25 micrometres, said coating containing at least one moiety selected from the group consisting of silicides, nitrides, carbides, borides, oxides, sulphides and mixtures thereof; (b) a detergent selected from at least one of the group consisting of a phenate salt, a sulphonate salt, a salixarate salt and mixtures thereof; and (c) an oil of lubricating viscosity. The invention further relates to the use of the composition to decrease engine wear, decrease sludge formation, filter plugging, decrease sulphur emissions and decrease phosphorus emissions.

FIELD OF INVENTION

The present invention relates to a lubricated engine part compositionwith a partial hard surface coating of average thickness in combinationwith detergents and an oil of lubricating viscosity. The composition hasimproved antiwear performance and/or decreased filter plugging.

BACKGROUND OF THE INVENTION

It is well known for lubricating oils to contain a number of additivesused to protect the engine from wear, the accumulation of sludge andfilter plugging. Common additives for engine lubricating oils are zincalkyldithiophosphate (ZDDP) an antiwear additive, and overbased calciumsulphonate detergents. It is believed that ZDDP antiwear additivesprotect the engine by forming a protective film on metal surfaces.Typical treatment quantities of ZDDP range from 1 to 2 weight percentbased on the total weight of the lubricant. Detergents such as overbasedcalcium sulphonate help keep the engine parts clean of soot and otherdeposits, and offer an alkalinity reserve. Typical treatment quantitiesof detergents range from 0.05 to 10 weight percent based on the totalweight of the lubricant.

In recent years phosphates and sulphonates derived from enginelubricants have been shown to contribute in part to particulateemissions. Further, sulphur and phosphorus tend to poison the NO_(x)catalysts used in catalytic converters, resulting in a reduction inperformance of said catalysts. Any reduction in the performance ofcatalytic converters tends to result in increased amounts of greenhousegases such as nitric oxide and/or sulphur oxides. However, reducing theamount phosphates and sulphonates by decreasing the amount of ZDDPand/or calcium sulphonate detergents will increase the amount of wear inan engine especially on engine parts with high loading for instance inthe valve train and increase the amount of sludge formed. Converselyreducing the amount phosphates and sulphonates will decrease filterplugging because divalent metals such as zinc and calcium are known tohelp form material capable of plugging filters, for instance,sulphonated ash.

The valve train metal parts are often iron or steel and these arechemically or physically modified to provide better antiwearperformance. The process often involves heating the metal part to aboveabout 600° C. followed by rapid cooling (or quenching) in water and/oran oil of lubricating viscosity. The metal part is then suitable for useand provides good protection against wear in the presence of antiwearadditives such as ZDDP. However ZDDP has the disadvantages mentionedabove.

Therefore there is a need for an engine part to be lubricated with acomposition capable of reducing sulphur and phosphorus content withouthaving an adverse effect on antiwear performance, sludge formation orincreased filter plugging.

It would be desirable to have a lubricated part capable of decreasingwear of said part. The present invention provides a lubricated partcapable of decreasing wear of said part.

It would be desirable to have a lubricated part capable of decreasingfilter plugging. The present invention provides a lubricated partcapable of decreasing filter plugging.

It would be desirable to have a lubricated part capable of decreasingsludge formation. The present invention provides a lubricated partcapable of decreasing sludge formation.

It would be desirable to have a lubricated part capable of decreasingphosphorus emissions. The present invention provides a lubricated partcapable of decreasing phosphorus emissions.

It would be desirable to have a lubricated part capable of decreasingsulphur emissions. The present invention provides a lubricated partcapable of decreasing sulphur emissions.

It would be desirable to have a lubricated part capable of decreasingthe amount of sulphonated ash. The present invention provides alubricated part capable of decreasing the amount of sulphonated ash.

SUMMARY OF THE INVENTION

The present invention provides a lubricated part comprising:

(a) a part with at least a partial hard surface coating of averagethickness less than about 25 micrometres, said coating containing atleast one moiety selected from the group consisting of silicides,nitrides, carbides, borides, oxides, sulphides and mixtures thereof;

(b) a detergent selected from at least one of the group consisting of aphenate salt, a sulphonate salt, a salixarate salt and mixtures thereof,and

(c) an oil of lubricating viscosity.

The invention further provides a lubricated part comprising:

(a) a part with at least a partial hard surface coating of averagethickness less than about 25 micrometres, said coating containing atleast one tungsten moiety selected from the group consisting ofsilicides, nitrides, carbides, borides, oxides, sulphides and mixturesthereof;

(b) a detergent package comprising:

-   -   (i) a phenate salt;    -   (ii) a sulphonate salt; and

(c) an oil of lubricating viscosity.

The invention further provides a lubricated part comprising:

(a) a part with at least a partial hard surface coating of averagethickness less than about 25 micrometres, said coating containing atleast one chromium moiety selected from the group consisting ofsilicides, nitrides, carbides, borides, oxides, sulphides and mixturesthereof;

(b) a salixarate salt detergent; and

(c) an oil of lubricating viscosity.

The invention further provides a method for lubricating a part, whereinthe lubricated part has at least one property selected from the groupconsisting of decreased wear, decreased filter plugging, decreasedsludge formation, decreased phosphorus emissions, decreased sulphuremissions, decreased sulphated ash formation and mixtures thereof; themethod comprising a lubricated part comprising.

(a) a part with at least a partial hard surface coating of averagethickness less than about 25 micrometres, said coating containing atleast one moiety selected from the group consisting of silicides,nitrides, carbides, borides, oxides, sulphides and mixtures thereof;

(b) a detergent selected from at least one of the group consisting of aphenate salt, a sulphonate salt, a salixarate salt and mixtures thereof;and

(c) an oil of lubricating viscosity.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a lubricated part comprising:

(a) a part with at least a partial hard surface coating of averagethickness less than about 25 micrometres, said coating containing atleast one moiety selected from the group consisting of silicides,nitrides, carbides, borides, oxides, sulphides and mixtures thereof;

(b) a detergent selected from at least one of the group consisting of aphenate salt, a sulphonate salt, a salixarate salt and mixtures thereof;and

(c) an oil of lubricating viscosity.

In one aspect of the invention provides a lubricated part comprising:

(a) a part with at least a partial hard surface coating of averagethickness less than about 25 micrometres, said coating containing atleast one tungsten moiety selected from the group consisting ofsilicides, nitrides, carbides, borides, oxides, sulphides and mixturesthereof;

(b) a detergent package comprising:

-   -   (i) a phenate salt;    -   (ii) a sulphonate salt; and

(c) an oil of lubricating viscosity.

In one aspect of the invention provides a lubricated part comprising:

(a) a part with at least a partial hard surface coating of averagethickness less than about 25 micrometres, said coating containing atleast one chromium moiety selected from the group consisting ofsilicides, nitrides, carbides, borides, oxides, sulphides and mixturesthereof;

(b) a salixarate salt detergent; and

(c) an oil of lubricating viscosity.

In one aspect of the invention provides a method for lubricating a part,wherein the lubricated part has at least one property selected from thegroup consisting of decreased wear, decreased filter plugging, decreasedsludge formation, decreased phosphorus emissions, decreased sulphuremissions, decreased sulphated ash formation and mixtures thereof, themethod comprising a lubricated part comprising:

(a) a part with at least a partial hard surface coating of averagethickness less than about 25 micrometres, said coating containing atleast one moiety selected from the group consisting of silicides,nitrides, carbides, borides, oxides, sulphides and mixtures thereof;

(b) a detergent selected from at least one of the group consisting of aphenate salt, a sulphonate salt, a salixarate salt and mixtures thereof;and

(c) an oil of lubricating viscosity.

In one aspect of the invention provides a method for lubricating a part,wherein the lubricated part has at least one property selected from thegroup consisting of decreased wear, decreased filter plugging, decreasedsludge formation, decreased phosphorus emissions, decreased sulphuremissions, decreased sulphated ash formation and mixtures thereof; themethod comprising a lubricated part comprising:

(a) a part with at least a partial hard surface coating of averagethickness less than about 25 micrometres, said coating containing atleast one tungsten moiety selected from the group consisting ofsilicides, nitrides, carbides, borides, oxides, sulphides and mixturesthereof;

(b) a detergent package comprising:

-   -   (i) a phenate salt;    -   (ii) a sulphonate salt; and

(c) an oil of lubricating viscosity.

In one aspect of the invention provides a method for lubricating a part,wherein the lubricated part has at least one property selected from thegroup consisting of decreased wear, decreased filter plugging, decreasedsludge formation, decreased phosphorus emissions, decreased sulphuremissions, decreased sulphated ash formation and mixtures thereof; themethod comprising a lubricated part comprising:

(a) a part with at least a partial hard surface coating of averagethickness less than about 25 micrometres, said coating containing atleast one chromium moiety selected from the group consisting ofsilicides, nitrides, carbides, borides, oxides, sulphides and mixturesthereof;

(b) a salixarate salt detergent; and

(c) an oil of lubricating viscosity.

Lubricated Part

The lubricated part can be metal or a non-metal, for instance apolymeric material or a ceramic material, although metal parts arepreferred. Typically the lubricated part can be located in an engine,the drive train or other areas where there can be boundary lubrication.Preferably the lubricated part can be located in an engine. Often thelubricated part can include parts within the engine such as acrankshaft, a piston, a piston ring, auxiliary components the valvetrain, fuel injector train or mixtures thereof. Preferably thelubricated part can include the valve train components such as acamshaft, a cam follower, a valve adjuster, a crosshead, a rocker arm, arocker arm pad, a lobe, a push rod or mixtures thereof; or the fuelinjector train such as an injector adjuster. In one embodiment thelubricated part is the rocker arm and rocker arm pads. In one embodimentthe lubricated part is the cam follower and the cam lobe. In oneembodiment the lubricated part is the crosshead. In one embodiment thelubricated part is the valve adjuster. In one embodiment the lubricatedpart is the injector adjuster.

Partial Hard Surface Coating

The partial hard surface coating of the invention are known in the artand are typically used to in areas where there is a need for boundarylubrication, for instance, metal to metal contact. The partial hardsurface coating is applied to the surface in a sufficient amount tocover the contact area i.e. where boundary lubrication is required.Typically a partial hard surface will have an average thickness lessthan about 25 micrometres, preferably less than about 20 micrometres,more preferably less than about 15 micrometres, even more preferablyless than about 12 micrometres and even more preferably less than about8 micrometres. Often the average coating thickness will be in the rangeabout 50 nanometres to about 25 micrometres, preferably about 100nanometres to about 20 micrometres, more preferably about 300 nanometresto about 15 micrometres, even more preferably about 600 nanometres toabout 10 micrometres and even more preferably about 900 nanometres toabout 5 micrometres. In one embodiment the average coating thickness isbetween about 3 micrometres and about 5 micrometres. In one embodimentthe average coating thickness is between about 2 micrometres and about 4micrometres.

The partial hard surface coating contains at least one moiety selectedfrom the group consisting of silicides, nitrides, carbides, borides,oxides, sulphides and mixtures thereof. Preferably the coating containsat least one moiety selected from the group consisting of nitrides,carbides and mixtures thereof. In one embodiment the coating containsnitrides. In one embodiment the coating contains carbides. In oneembodiment the coating can include sulphides such as molybdenumsulphide. In one embodiment the coating can be substantially free of tofree of sulphides such as molybdenum sulphide. In one embodiment thecoating can include oxides such as tungsten oxide. In one embodiment thecoating can be substantially free of to free of oxides such as tungstenoxide.

Typically the silicides, nitrides, carbides, borides, oxides andsulphides incorporate at least one metal selected from the groupconsisting of Group IVb of the periodic table, Group Vb of the periodictable Group VIb of the periodic table and mixtures thereof. Examples ofsuitable metals include chromium, molybdenum, tungsten, vanadium,titanium or mixtures thereof. Preferably the metals are selected fromthe group consisting of chromium, tungsten, vanadium and mixturesthereof. In one embodiment the metal is chromium. In one embodiment themetal is tungsten.

The partial hard surface coating can be selected from at least one ofvanadium silicide, vanadium nitride, vanadium carbide, vanadium boride,vanadium oxide, vanadium sulphide, tungsten silicide, tungsten nitride,tungsten carbide, tungsten boride, tungsten oxide, tungsten sulphide,chromium silicide, chromium nitride, chromium carbide, chromium boride,chromium oxide, chromium sulphide and mixtures thereof. Typically thepartial hard surface coating will have a Vickers hardness (VHN) fromabout 700 to about 2500, preferably about 800 to about 2000 and evenmore preferably about 900 to about 1900. In one embodiment the VHN isfrom about 900 to about 1350.

In one embodiment the partial hard surface coating is tungsten carbide.Typically tungsten carbide has a VHN hardness of 700 or more, preferably850 or more and more preferably 950 or more. In one embodiment thehardness is about 1000. In one embodiment the average coating thicknessis between about 2 to about 4 micrometres. A typical commerciallyavailable tungsten carbide coating suitable for the invention isBalinit®C. This tungsten carbide coating is available from BalzersLimited.

In one embodiment the partial hard surface coating is chromium nitride.Typically chromium nitride has a hardness of 1200 or more, preferably1450 or more and more preferably 1600 or more Vickers hardness (VHN). Inone embodiment the hardness is about 1750 VHN. In one embodiment theaverage coating thickness is between about 3 to about 5 micrometres. Atypical commercially available chromium nitride coating suitable for theinvention is Balinit®D. This chromium nitride coating is available fromBalzers Limited.

The partial hard surface coating can be deposited onto the part to belubricated as a singular layer or as part of multi layer. A multi layercan have one or more of the coatings described above, for example achromium nitride layer and then a tungsten carbide layer. Also in someinstances an adhesive layer may be required. In one embodiment thepartial hard surface coating is deposited as a single layer.

The partial hard surface coating can be deposited onto the part to belubricated by a number of techniques, for instance, physical vapourdeposition (PVD), chemical vapour deposition (CVD), ion beam deposition(also referred to as IBD or IBAD), ion beam enhanced deposition (IBED)and plasma induced immersion process techniques. Preferably the partialhard surface coating can be deposited onto the part to be lubricated byphysical vapour deposition. Typical physical vapour depositiontechniques include PVD ion plating or PVD magnetron sputtering. In oneembodiment the partial hard surface coating is deposited by PVD ionplating. In one embodiment the partial hard surface coating is depositedby PVD magnetron sputtering.

As used herein, the term “hydrocarbyl substitutent” or “hydrocarbylgroup” is used in its ordinary sense, which is well-known to thoseskilled in the art. Specifically, it refers to a group having a carbonatom directly attached to the remainder of the molecule and havingpredominantly hydrocarbon character. Examples of hydrocarbyl groupsinclude:

hydrocarbon substitutents, that is, aliphatic (e.g., alkyl or alkenyl),alicyclic (e.g., cycloalkyl, cycloalkenyl) substitutents, and aromatic-,aliphatic-, and alicyclic-substituted aromatic substitutents, as well ascyclic substitutents wherein the ring is completed through anotherportion of the molecule (e.g., two substitutents together form a ring);

substituted hydrocarbon substitutents, that is, substitutents containingnon-hydrocarbon groups which, in the context of this invention, do notalter the predominantly hydrocarbon nature of the substitutent (e.g.,halo (especially chloro and fluoro), hydroxy, alkoxy, mercapto,alkylmercapto, nitro, nitroso, and sulfoxy); %

hetero substitutents, that is, substitutents which, while having apredominantly hydrocarbon character, in the context of this invention,contain other than carbon in a ring or chain otherwise composed ofcarbon atoms. Heteroatoms include sulfur, oxygen, nitrogen, andencompass substitutents as pyridyl, furyl, thienyl and imidazolyl. Ingeneral, no more than two, preferably no more than one, non-hydrocarbonsubstitutent will be present for every ten carbon atoms in thehydrocarbyl group; typically, there will be no non-hydrocarbonsubstitutents in the hydrocarbyl group.

Sulphonate Salt Detergent

The substrate of the sulphonate detergent of the composition can berepresented by the formula (R¹)_(k)-Z—SO₃M: wherein, each R¹ isindependently an alkyl, cycloalkyl, aryl, acyl, or other hydrocarbylgroup with a 6 to 40, preferably 8 to 25 and even more preferably 9 to20 carbon atoms; Z can be independently a cyclic or acyclic hydrocarbongroup; M can be hydrogen, a valence of a metal ion, an ammonium ion andmixtures thereof, provided hydrogen is present on less than 50%,preferably less than 30%, more preferably less than 20%, even morepreferably less than 10% and even more preferably less than 5% of theavailable M entities; and k is an integer between 1 and 5, for example1, 2, 3, 4, 5 or mixtures thereof. Preferably k is between 1 and 3, morepreferably 1 or 2 and even more preferably 1.

In one embodiment k is 1 and R¹ is a branched alkyl group with 6 to 40carbon atoms. In one embodiment k is 1 and R¹ is a linear alkyl groupwith 6 to 40 carbon atoms.

The most preferred sulphonate components are calcium polypropenebenzenesulphonate; and calcium monoalkyl- and/ordialkyl-benzenesulphonate wherein the alkyl groups contain at least 10carbon atoms, for example, 11 carbon atoms, 12 carbon atoms, 13 carbonatoms, 14 carbon atoms, 15 carbon atoms and mixtures thereof.

When M is a valence of a metal ion, the metal can be monovalent,divalent, trivalent or mixtures of such metals. When monovalent, themetal M can be an alkali metal, preferably lithium, sodium, orpotassium; and more preferably potassium, which can be used alone or incombination with other metals. When divalent, the metal M can be analkaline earth metal, preferably magnesium, calcium, barium or mixturesof such metals, more preferably calcium, which can be used alone or incombination with other metals. When trivalent, the metal M can bealuminum, which can be used alone or in combination with other metals.In one embodiment the metal is an alkaline earth metal. In oneembodiment the metal is calcium, which can be used alone or incombination with other metals.

When Z is cyclic hydrocarbon group, suitable groups include phenyl orfused bicyclic groups such as naphthalene, indenyl, indanyl,bicyclopentadienyl and mixtures thereof. Although Z can be a fusedbicyclic ring, benzene rings are preferred.

When Z is an acyclic hydrocarbon group, the carbon chain can be linearor branched, although linear is preferred. Suitable groups includederivatives of carboxylic acids containing 7 to 30, preferably 7 to 20,more preferably 8 to 20 and even more preferably 8 to 15 carbon atoms.Further the chain can be saturated or unsaturated, although saturated ispreferred.

Typically an overbased sulphonate detergent has a TBN (total basenumber) in the range of about 300 to about 600, preferably about 310 toabout 580, more preferably about 320 to about 540 and even morepreferably about 330 to about 510. In one embodiment the overbasedsulphonate detergent has a TBN of about 400. The overbased sulphonatedetergent may be used alone or with other detergents.

The sulphonate detergent can overbased or non-overbased, althoughoverbased is preferred. Overbased material, otherwise referred to asoverbased or superbased salts, are generally single phase, homogeneousNewtonian systems characterised by a metal content in excess of thatwhich would be present for neutralisation according to the stoichiometryof the metal and the particular acidic organic compound reacted with themetal. The overbased materials are prepared by reacting an acidicmaterial (typically an inorganic acid or lower carboxylic acid,preferably carbon dioxide) with a mixture comprising an acidic organiccompound, a reaction medium comprising at least one inert, organicsolvent (mineral oil, naphtha, toluene, xylene, etc.) for said acidicorganic material, a stoichiometric excess of a metal base, and apromoter such as a phenol or alcohol. A mixture of alcohols typicallycontains methanol and at least one alcohol with 2 to 7 carbon atoms. Theacidic material will normally have a sufficient number of carbon atomsto provide a degree of solubility in oil. The amount of excess metal iscommonly expressed in terms of metal ratio. The term “metal ratio” isthe ratio of the total equivalents of the metal to the equivalents ofthe acidic organic compound. A neutral metal salt has a metal ratio ofone. A salt having 4.5 times as much metal as present in a normal saltwill have metal excess of 3.5 equivalents, or a ratio of 4.5.

When present, the sulphonate detergent is typically present at about0.05 to about 20, preferably about 0.1 to about 10, and more preferablyabout 0.2 to about 8 and even more preferably about 0.5 to about 5weight percent of the lubricating oil composition.

Salixarate Salt Detergent

The substrate of the salixarate detergent of the invention can berepresented by a substantially linear compound comprising at least oneunit of the formulae (I) or (II):

each end of the compound having a terminal group of formulae (III) or(IV):

such groups being linked by divalent bridging groups A, which may be thesame or different for each linkage; wherein in formulas (I)-(IV) R³ ishydrogen or a hydrocarbyl group; R² is hydroxyl or a hydrocarbyl groupand j is 0, 1, or 2; R⁶ is hydrogen, a hydrocarbyl group, or ahetero-substituted hydrocarbyl group; either R⁴ is hydroxyl and R⁵ andR⁷ are independently either hydrogen, a hydrocarbyl group, orhetero-substituted hydrocarbyl group, or else R⁵ and R⁷ are bothhydroxyl and R⁴ is hydrogen, a hydrocarbyl group, or ahetero-substituted hydrocarbyl group; provided that at least one of R⁴,R⁵, R⁶ and R⁷ is hydrocarbyl containing at least 8 carbon atoms; andwherein the molecules on average contain at least one of unit (I) or(III) and at least one of unit (II) or (IV) and the ratio of the totalnumber of units (I) and (III) to the total number of units of (II) and(IV) in the composition is about 0.1:1 to about 2:1.

The divalent bridging group “A,” which may be the same or different ineach occurrence, includes —CH₂— (methylene bridge) and —CH₂OCH₂— (etherbridge), either of which may be derived from formaldehyde or aformaldehyde equivalent (e.g., paraform, formalin).

Salixarate derivatives and methods of their preparation are described ingreater detail in U.S. Pat. No. 6,200,936 and PCT Publication WO01/56968. It is believed that the salixarate derivatives have apredominantly linear, rather than macrocyclic, structure, although bothstructures are intended to be encompassed by the term “salixarate.”

Preparative Example. Overbased Salixarate

Step (a). A reactor is charged with 15 kg (23.3 moles) of polyisobutenyl( M _(n) 550) substituted phenol and 10.7 kg 150 N mineral oil. Thematerials are heated, under nitrogen, to 35° C., then 120 g (1.07 moles)aqueous KOH is added via a pump and charge line, which is subsequentlywashed into the reactor with 100 mL distilled water. The mixture isheated to 75° C. over 0.5 hour and 2.6 kg (32.1 moles) of 37% aqueousformaldehyde is added via a pump and charge line over 0.5 hour,subsequently washed into the reactor with 300 mL distilled water. Themixture is held at temperature for 2 hours, whereupon 1.65 kg salicylicacid (12 moles) is added followed by heating to 99° C. and reflux. Thereaction mixture is further heated to 140° C. over 1 hour, removing 2.6L aqueous distillate. The mixture is maintained at 140° C. for 1.5 hourat atmospheric pressure, followed by 0.5 hour at 60 kPa (0.6 bar),collecting some additional aqueous distillate.

Step (b). A reactor is charged with 13.0 kg (8.95 moles) of the cooledproduct of step (a), 2.33 kg (31.5 moles) Ca(OH)₂, and 450 g ethyleneglycol. While stirring, 7.38 kg of 2-ethylhexanol are added over 0.3hours. The mixture is heated at 95° C. at reduced pressure (80 kPa to 44kPa [0.2 to 0.56 bar vacuum]) over ¾ hour, followed by 130° C. over ¼hour at 80 kPa (0.2 bar vacuum), during which time 0.5 L aqueousdistillate is collected. An additional 2.16 kg ethylene glycol is addedis added over about 0.3 hour at 125 to 130° C. Pressure is reduced to 90kPa (0.1 bar vacuum) and then carbon dioxide is passed into the mixtureat 500 g/hour until a total of 750 g is added. After carbonation iscomplete, the temperature is increased to 200° C. and the pressurereduced to 44 kPa (0.56 bar vacuum) and maintained for a total of about2.2 hours, during which time 9.5 L aqueous distillate is collected. Theproduct is an overbased calcium salixarate.

It is believed that a significant fraction of salixarate molecules(prior to neutralisation) may be represented on average by the followingformula:

wherein each R⁸ can be the same or different, and are an alkyl group,and, in a preferred embodiment, is a polyisobutene group (especially ofmolecular weight 200 to 1,000, or about 550). Significant amounts of di-or trinuclear species may also be present containing one salicylic endgroup of formula (III). The salixarate detergent may be used alone orwith other detergents.

When present, the salixarate detergent is typically present at about0.05 to about 20, preferably about 0.1 to about 10, and more preferablyabout 0.2 to about 8 and even more preferably about 0.5 to about 5weight percent of the lubricating oil composition.

Phenate Salt Detergent

The substrate of the phenate detergent of the composition can berepresented by the formulae:

wherein the number of sulphur atoms in formula (VI) y, can be in therange from 1 to 8, preferably 1 to 6 and even more preferably 1 to 4;the number of (CR¹⁰CR¹¹) moieties y in formula (VII), can be in therange from 0 to 8, preferably 0 to 4 and even more preferably 0 to 2. Inone embodiment y=1 in formula (VI), and the phenate detergent is oftendescribed in the art as a sulphur containing phenate. In one embodimenty=0 in formula (VII), and the phenate detergent is often described inthe art as “normal.” In one embodiment y=1 in formula (VII), and thephenate detergent is often described in the art as “alkylene coupled”,especially “methylene coupled.”

R⁹ can be the same or different and are independently hydrogen or ahydrocarbyl group. When R⁹ is hydrocarbyl group, a preferred group is analkyl group, and, in a more preferred embodiment, is a polyisobutenegroup (especially of molecular weight 200 to 1,000, or about 550); T ishydrogen or an (S)_(y) linkage terminating in hydrogen, an ion or anon-phenolic hydrocarbyl group; and M is as described above for thesulphonate detergent.

x is an integer and present in a sufficient number of times to formoligomers of hydrocarbyl phenol. Oligomers are described as dimers,trimers, tetramers, pentamers and hexamers when x is equal to 0, 1, 2,3, 4, 5 and 6 respectively to form a substrate. Typically the number ofoligomers represented by x can be in the range from 0 to 10, preferably0 to 9, more preferably 0 to 8, even more even more preferably 0 to 6and even more preferably 0 to 4.

The number of R⁹ and/or substitutents other than hydrogen on eachhydrocarbyl phenol ring w, can be in the range from 0 to 3, morepreferably 1 to 2 and even more preferably 1, provided at least onehydrocarbyl group is present on an oligomer. In one embodiment w is 1and located at para position relative to the OM group. Typically, theminimum number of carbon atoms present on all hydrocarbyl groups toensure oil solubility can be 8 or preferably 9. When two or morehydrocarbyl groups are present in the same substrate molecule, they maybe the same or different. R¹⁰ and R¹¹ can be hydrogen or hydrocarbyl ormixtures thereof, preferably at least one is hydrogen and even morepreferably both are hydrogen.

Typically the sulphur containing phenate detergent has a TBN in therange of 30 to 300, preferably 80 to 290, more preferably 100 to 280 andeven more preferably 120 to 270. In one embodiment the sulphurcontaining phenate detergent has a TBN of about 250. The sulphurcontaining phenate detergent may be used alone or with other sulphurcontaining phenate detergents.

When present, the phenate detergent is typically present at about 0.05to about 20, preferably about 0.1 to about 10, and more preferably about0.2 to about 8 and even more preferably about 0.5 to about 5 weightpercent of the lubricating oil composition.

Oils of Lubricating Viscosity

The lubricating oil composition of the present invention can be added toan oil of lubricating viscosity. The oil includes natural and syntheticoils, oil derived from hydrocracking, hydrogenation, hydrofinishing,unrefined, refined and re-refined oils, or mixtures thereof.

Unrefined oils are those obtained directly from a natural or syntheticsource generally without (or with little) further purificationtreatment.

Refined oils are similar to the unrefined oils except they have beenfurther treated in one or more purification steps to improve one or moreproperties. Purification techniques are known in the art and includesolvent extraction, secondary distillation, acid or base extraction,filtration, percolation and the like.

Re-refined oils are also known as reclaimed or reprocessed oils, and areobtained by processes similar to those used to obtain refined oils andoften are additionally processed by techniques directed to removal ofspent additives and oil breakdown products.

Natural oils useful in making the inventive lubricants include animaloils, vegetable oils (e.g., castor oil, lard oil), mineral lubricatingoils such as liquid petroleum oils and solvent-treated or acid-treatedmineral lubricating oils of the paraffinic, naphthenic or mixedparaffinic-naphthenic types and oils derived from coal or shale ormixtures thereof.

Synthetic lubricating oils are useful and include hydrocarbon oils suchas polymerised and interpolymerised olefins (e.g., polybutylenes,polypropylenes, propyleneisobutylene copolymers); poly(1-hexenes),poly(1-octenes), poly(1-decenes), and mixtures thereof; alkyl-benzenes(e.g. dodecylbenzenes, tetradecylbenzenes, dinonylbenzenes,di-(2-ethylhexyl)-benzenes); polyphenyls (e.g., biphenyls, terphenyls,alkylated polyphenyls); alkylated diphenyl ethers and alkylated diphenylsulphides and the derivatives, analogs and homologs thereof or mixturesthereof.

Other synthetic lubricating oils include but are not limited to polyolesters, liquid esters of phosphorus-containing acids (e.g., tricresylphosphate, trioctyl phosphate, and the diethyl ester of decanephosphonic acid), and polymeric tetrahydrofurans. Synthetic oils may beproduced by Fischer-Tropsch reactions and typically may behydroisomerised Fischer-Tropsch hydrocarbons or waxes.

Oils of lubricating viscosity can also be defined as specified in theAmerican Petroleum Institute (API) Base Oil InterchangeabilityGuidelines. The five base oil groups are as follows: Group I (sulphurcontent >0.03 wt %, and/or <90 wt % saturates, viscosity index 80-120);Group II (sulphur content ≦0.03 wt %, and ≧90 wt % saturates, viscosityindex 80-120); Group III (sulphur content ≦0.03 wt %, and ≧90 wt %saturates, viscosity index ≦120); Group IV (all polyalphaolefins(PAO's)); and Group V (all others not included in Groups I, II, III, orIV). The oil of lubricating viscosity is selected from the groupconsisting of API Group I, II, III, IV, V oil and mixtures thereof.Preferably the oil of lubricating viscosity is selected from the groupconsisting of API Group II, III, or IV oil and mixtures thereof. If theoil of lubricating viscosity is an API Group II, III, or IV oil therecan be up to a maximum of about 49.9 wt %, preferably up to a maximum ofabout 40 wt %, more preferably up to a maximum of about 30 wt %, evenmore preferably up to a maximum of about 20 wt %, even more preferablyup to a maximum of about 10 wt % and even more preferably up to amaximum of about 5 wt % of the lubricating oil an API Group I or V oil.

The oil of lubricating viscosity is typically present at about 5 toabout 99.8, preferably about 42 to about 98.7, and more preferably about55.2 to about 97.3 and even more preferably about 69.3 to about 95.4weight percent of the lubricating oil composition.

If the present invention is in the form of a concentrate (which can becombined with additional oil to form, in whole or in part, a finishedlubricant), the ratio of each of the above-mentioned dispersant, as wellas other components, to diluent oil is typically in the range of about80:20 to about 10:90 by weight.

Metal Hydrocarbyl Dithiophosphate

The invention can further contain a metal hydrocarbyl dithiophosphatethat can be represented by the formula:

wherein R¹² and R¹³ are independently hydrogen, hydrocarbyl groups ormixtures thereof, provided that at least one of R¹² and R¹³ is ahydrocarbyl group, preferably alkyl or cycloalkyl with 1 to about 30,preferably about 2 to about 20 and even more preferably about 2 to about15 carbon atoms.

M′ is a metal, and n is an integer equal to the available valence of M′.M′ is mono- or di- or tri- valent, preferably divalent, more preferablya divalent transition metal. In one embodiment M′ is zinc. In oneembodiment M′ is calcium. In one embodiment M′ is barium.

Examples of suitable zinc hydrocarbyl dithiophosphates (often referredto as ZDDP, ZDP or ZDTP) can include zinc isopropyl methylamyldithiophosphate, zinc isopropyl isooctyl dithiophosphate, bariumdi-(nonyl)-dithiophosphate, zinc di-(cyclohexyl) dithiophosphate, zincdi-(isobutyl) dithiophosphate, calcium di-(hexyl) dithiophosphate, zincisobutyl isoamyl dithiophosphate, zinc isopropyl n-butyldithiophosphate, isobutyl primary amyl dithiophosphate, methylamyldithiophosphate, isopropyl 2-ethylhexyl dithiophosphate, and mixturesthereof. Other suitable metal hydrocarbyl dithiophosphates includebarium di-(nonyl)-dithiophosphate, calcium di-(hexyl) dithiophosphateand mixtures thereof.

The metal hydrocarbyl dithiophosphates can typically be present at 0 toabout 5, preferably about 0.01 to about 3, and more preferably about0.05 to about 0.8 and even more preferably about 0.07 to about 0.7 wt %of the lubricating oil composition. In one embodiment the metalhydrocarbyl dithiophosphates are present at less than 1 wt % of thelubricating oil composition. In one embodiment the metal hydrocarbyldithiophosphates are present at less than 0.8 wt % of the lubricatingoil composition. In one embodiment the metal hydrocarbyldithiophosphates are present at less than 0.6 wt % of the lubricatingoil composition. In one embodiment the metal hydrocarbyldithiophosphates can be present at about 0.5 weight percent of thelubricating oil composition.

Borated Ester

The invention may further contain a borate ester friction modifier. Theborate ester can be prepared by the reaction of a boron compound and atleast one compound selected from epoxy compounds, halohydrin compounds,epihalohydrin compounds, alcohols and mixtures thereof. Typically thealcohols include monohydric alcohols, dihydric alcohols, trihydricalcohols or higher alcohols. Hereinafter “epoxy compound or equivalentis used when referring to “at least one compound selected from epoxycompounds, halohydrin compounds, epihalohydrin compounds, alcohols andmixtures thereof.”

Boron compounds suitable for preparing the borate ester include thevarious forms selected from the group consisting of boric acid(including metaboric acid, HBO₂, orthoboric acid, H₃BO₃, and tetraboricacid, H₂B₄O₇), boric oxide, boron trioxide and alkyl borates. The borateester can also be prepared from boron halides.

The borate ester formed by the reaction of a boron compound and an epoxycompound or equivalent can be represented by at least one formulaselected from:

wherein R¹⁴, R¹⁵ and R¹⁶ can be hydrogen or hydrocarbyl groups providedat least one, preferably at least two of R¹⁴, R¹⁵ and R¹⁶ arehydrocarbyl groups. In one embodiment, R¹⁴ is a hydrocarbyl group; andR's and R¹⁶ are hydrogen. In one embodiment, R¹⁴ and R¹⁵ are hydrocarbylgroups and R¹⁶ is hydrogen. In one embodiment R¹⁴, R¹⁵ and R¹⁶ are allhydrocarbyl groups. The hydrocarbyl groups can be alkyl, aryl orcycloalkyl when any 2 adjacent R groups are connected in a ring. Whenalkyl, the group can be saturated or unsaturated, although unsaturatedis preferred. In one embodiment the hydrocarbyl group is cyclic. In oneembodiment the hydrocarbyl groups are mixtures of alkyl and cycloalkyl.

Typically there is no upper limit on the number of carbon atoms, but apractical limit is about 500, preferably about 400, more preferablyabout 200, even more preferably about 100 or about 60. For example thenumber of carbon atoms present in R¹⁴, R¹⁵ and R¹⁶ can be 1 to about 60,preferably 1 to about 40 and more preferably 1 to about 30 carbon atoms,provided the total number of carbon atoms in R¹⁴, R¹⁵ and R¹⁶ is about 9or more, preferably about 10 or more, more preferably about 12 or moreor about 14 or more.

In one embodiment R¹⁴, R¹⁵ and R¹⁶ are all hydrocarbyl groups containing1 to about 30 carbon atoms, provided the total number of carbon atoms inR¹⁴, R¹⁵ and R¹⁶ is about 9 or more.

R¹⁷ to R²³ inclusive can be hydrogen or hydrocarbyl groups, provided atleast one of R¹⁷ to R²⁰ and/or R²¹ to R²³ is a hydrocarbyl group. R²⁴ toR²⁹ inclusive are hydrocarbyl groups or hydrogen, although hydrocarbylgroups are preferred; and R³⁰ can be hydrogen or a hydrocarbyl group,although hydrogen is preferred. The hydrocarbyl group definition for R¹⁷to R³⁰ inclusive is the same as the definition given for R¹⁴, R¹⁵ andR¹⁶.

Examples of groups suitable for R¹⁴ to R³⁰ inclusive include isopropyl,n-butyl, isobutyl, amyl, 2-pentenyl, 4-methyl-2-pentyl, 2-ethyl-1-hexyl,2-ethylhexyl, heptyl, isooctyl, nonyl, decyl, undecyl, dodecenyl,dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl,octadecyl, nonadecyl and eicosyl groups.

The borated ester can be present from about 0 to about 20, preferablyabout 0.1 to about 15, more preferably about 0.3 to about 10 and evenmore preferably about 0.5 to about −5 weight percent of the lubricatingoil composition.

The epoxy compounds useful for preparing the borate ester of theinvention can be represented by the formulae:

wherein R³¹ can be an alkyl chain containing 8 to 30, preferably 10 to26 and even more preferably 12 to 22 carbon atoms; R³² can be hydrogenor an alkyl chain containing 1 to 4, preferably 1 to 2 carbon atoms,even more preferably R³² being hydrogen; and G can be hydrogen or ahalogen, that is, chlorine, bromine, iodine or fluorine or mixturesthereof, although chlorine is preferred. Even more preferably G ishydrogen. When G is a halogen, the epoxy compounds of the invention areepihalohydrin compounds.

In one embodiment the epoxy compounds of the invention includecommercial mixtures of C₁₄-C₁₆ epoxides or C₁₄-C₁₈ epoxides. In oneembodiment, the epoxy compounds of the invention have been purified.Examples of suitable purified epoxy compounds can include1,2-epoxydecane, 1,2-epoxyundecane, 1,2-epoxydodecane,1,2-epoxytridecane, 1,2-epoxybutadecane, 1,2-epoxypenta-decane,1,2-epoxyhexadecane, 1,2-epoxyheptadecane, 1,2-epoxyoctadecane,1,2-epoxyhonadecane and 1,2-epoxyicosane. Preferably purified epoxycompounds include 1,2-epoxytetradecane, 1,2-epoxypentadecane1,2-epoxyhexadecane 1,2-epoxyheptadecane, 1,2-epoxyoctadecane; and morepreferably 1,2-epoxyhexadecane.

Another group of compounds described as “epoxy compounds or equivalent”are alcohols and include monohydric alcohols, dihydric alcohols,trihydric alcohols, higher alcohols (that is, alcohols containing about4 or more hydroxy groups) and mixtures thereof, monohydric alcoholsbeing preferred. Typically the alcohol compounds contain about 2 toabout 30, more preferably about 4 to about 26 and even more preferablyabout 6 to about 20 carbon atoms. The alcohol compounds can includeglycerol compounds such as glycerol monooleate.

Other Performance Additives

The lubricated part is lubricated using a lubricating oil compositioncomprising (a) at least one detergent from component (b) of theinvention; an oil of lubricating viscosity from component (c) of theinvention; (c) optionally a metal hydrocarbyl dithiophosphate; (d)optionally a borate ester; and (e) other performance additives.

The other performance additives selected from the group consisting ofdetergents other than those of component (b) of the invention, metaldeactivators, dispersants, antioxidants, antiwear agents, corrosioninhibitors, antiscuffing agents, extreme pressure agents, foaminhibitors, demulsifiers, friction modifiers other than a borate ester,viscosity modifiers, pour point depressants, fluidity modifiers and sealswelling agents. Typically, fully-formulated lubricating oil willcontain one or more of these other performance additives.

The total combined amount of the other performance additives present canbe from about 0 to about 30, preferably about 1 to about 25, morepreferably about 2 to about 20 and even more preferably about 3 to about15 weight percent of the lubricating oil composition. Although one ormore of the other performance additives can be present, it is common forthe performance additives to be present in different amounts relative toeach other.

Typically antioxidants and/or viscosity modifiers are the most abundantand account for about 40 or more, preferably about 55 or more, morepreferably about 70 or more, even more preferably about 80 or more andeven more preferably about 90 or more wt % of the other performanceadditives in the lubricating oil composition. Typically antioxidants arepresent in about 2 to about 10 wt % of the lubricating oil composition,for example, 3 wt %, 4 wt %, 5 wt % or 6 wt %; Typically viscositymodifiers are present in about 2 to about 15 wt % of the lubricating oilcomposition, for example, 4 wt %, 5 wt % or 6 wt %, 7 wt % or 8 wt %.

Metal Deactivators

Metal deactivators can be used to neutralise the catalytic effect ofmetal for promoting oxidation in lubricating oil. Examples of metaldeactivators include but are not limited to derivatives ofbenzotriazoles, 1,2,4-triazoles, benzimidazoles,2-alkyldithiobenzimidazoles, 2-alkyldithiobenzothiazoles,2-(N,N-dialkyldithiocarbamoyl)benzothiazoles,2,5-bis(alkyl-dithio)-1,3,4-thiadiazoles,2,5-bis(N,N-dialkyldithiocarbamoyl)-1,3,4-thiadiazoles,2-alkyldithio-5-mercapto thiadiazoles and mixtures thereof. The metaldeactivator may be used alone or in combination with other metaldeactivators.

In one embodiment the metal deactivator is a derivative ofbenzotriazole. In one embodiment the metal deactivator is a2,5-bis(alkyl-dithio)-1,3,4-thiadiazole.

In one embodiment hydrocarbyl benzotriazoles substituted at positions 4-or 5- or 6- or 7- can be further reacted with an aldehyde and asecondary amine to form a Mannich product. Examples of suitable Mannichproducts includeN,N-bis(heptyl)-ar-methyl-1H-benzotriazole-1-methanamine,N,N-bis(nonyl)-ar-methyl-1H-benzotriazole-1-methanamine,N,N-bis(decyl)-ar-methyl-1H-benzotriazole-1-methanamine,N,N-bis(undecyl)-ar-methyl-1H-benzotriazole-1-methanamine,N,N-bis(dodecyl)-ar-methyl-1H-benzotriazole-1-methanamineN,N-bis(2-ethylhexyl)-ar-methyl-1H-benzotriazole-1-methan-amine andmixtures thereof. In one embodiment the metal deactivator isN,N-bis(2-ethylhexyl)-ar-methyl-1H-benzotriazole-1-methanamine.

In one embodiment the metal deactivator is a hydrocarbyl substitutedbenzotriazole compound. The benzotriazole compounds with hydrocarbylsubstitutions include at least one of the following ring positions 1- or2- or 4- or 5- or 6- or 7-. The hydrocarbyl groups contain 1 to 30,preferably 1 to 15, preferably 1 to 7 carbon atoms, and even morepreferably the metal deactivator is 5-methylbenzotriazole(tolyltriazole).

In one embodiment, the metal deactivator is a2,5-bis(alkyl-dithio)-1,3,4-thiadiazole. The alkyl groups of2,5-bis(alkyl-dithio)-1,3,4-thiadiazole contain 1 to about 30,preferably about 2 to about 25, more preferably 4 to about 20 and evenmore preferably about 6 to about 16 carbon atoms. Examples of suitable2,5-bis(alkyl-dithio)-1,3,4-thiadiazoles include but are not limited to2,5-bis(tert-octyldithio)-1,3,4-thiadiazole2,5-bis(tert-nonyldithio)-1,3,4-thiadiazole,2,5-bis(tert-decyldithio)-1,3,4-thiadiazole,2,5-bis(tert-undecyldithio)-1,3,4-thiadiazole,2,5-bis(tert-dodecyldithio)-1,3,4-thiadiazole,2,5-bis(tert-tridecyldithio)-1,3,4-thiadiazole,2,5-bis(tert-tetradecyldithio)-1,3,4-thiadiazole,2,5-bis(tert-pentadecyldithio)-1,3,4-thiadiazole,2,5-bis(tert-hexadecyldithio)-1,3,4-thiadiazole,2,5-bis(tert-heptadecyldithio)-1,3,4-thiadiazole,2,5-bis(tert-octadecyldithio)-1,3,4-thiadiazole,2,5-bis(tert-nonadecyldithio)-1,3,4-thiadiazole,2,5-bis(tert-eicosyldithio)-1,3,4-thiadiazole and mixtures thereof.Preferably a 2,5-bis(alkyl-dithio)-1,3,4-thiadiazole metal deactivatorcan be 2,5-bis(tert-nonyldithio)-1,3,4-thiadiazole or mixtures thereof.

Detergents

Detergents other than those of component (b) of the invention are knownand can include neutral or overbased, Newtonian or non-Newtonian, basicsalts of alkali, alkaline earth and transition metals with one or moreof carboxylic acid, phosphorus acid, mono- and/or di- thiophosphoricacid, saligenins or mixtures thereof. Commonly used metals includesodium, potassium, calcium, magnesium lithium or mixtures thereof. Mostcommonly used metals include sodium, magnesium and calcium.

Dispersants

Dispersants are often known as ashless-type dispersants because, priorto mixing in a lubricating oil composition they do not containash-forming metals; and they do not normally contribute any ash formingmetals when added to a lubricant and polymeric dispersants. Ashless typedispersants are characterised by a polar group attached to a relativelyhigh molecular weight hydrocarbon chain. Typical ashless dispersantsinclude N-substituted long chain alkenyl succinimides. Examples ofN-substituted long chain alkenyl succinimides include polyisobutylenesuccinimide with number average molecular weight in the range 350 to5000, preferably 500 to 3000. Succinimide dispersants and theirpreparation are disclosed, for instance in U.S. Pat. No. 4,234,435.

In one embodiment the invention further comprises at least onedispersant derived from polyisobutylene, an amine and zinc oxide to forma polyisobutylene succinimide complex with zinc. The polyisobutylenesuccinimide complex with zinc can be used alone or in combination withother dispersants.

Another class of ashless dispersant is Mannich bases. Mannichdispersants are the reaction products of alkyl phenols in which thealkyl group contains at least 30 carbon atoms with aldehydes (especiallyformaldehyde) and amines (especially polyalkylene polyamines).

Dispersants can also be post-treated conventional method by a reactionwith any of a variety of agents. Among these are urea, thiourea,dimercaptothiadiazoles, carbon disulfide, aldehydes, ketones, carboxylicacids, hydrocarbon-substituted succinic anhydrides, maleic anhydride,nitriles, epoxides, boron compounds, and phosphorus compounds.

Antiwear Agents

The lubricating oil composition may additionally contain an antiwearagent. Useful antiwear agents other than ZDDP include phosphoric acidesters or salt thereof; phosphites; and phosphorus-containing carboxylicesters, ethers, and amides or mixtures thereof.

Antioxidants

Antioxidants are known materials and include diphenylamines, stericallyhindered phenols, molybdenum dithiocarbamates and sulphurised olefins.

Examples of suitable diphenylamine antioxidants include octyldiphenylamine, nonyl diphenylamine, bis-octyl diphenylamine, bis-nonyldiphenylamine or mixtures thereof.

Examples of sterically hindered phenols can include2,6-di-tert-butylphenol, 4-Methyl-2,6-di-tert-butylphenol,4-ethyl-2,6-di-tert-butylphenol, 4-propyl-2,6-di-tert-butylphenol,4-butyl-2,6-di-tert-butylphenol 2,6-di-tert-butylphenol,4-pentyl-2,6-di-tert-butylphenol, 4-hexyl-2,6-di-tert-butylphenol,4-heptyl-2,6-di-tert-butylphenol,4-(2-ethylhexyl)-2,6-di-tert-butylphenol,4-octyl-2,6-di-tert-butylphenol, 4-nonyl-2,6-di-tert-butylphenol,4-decyl-2,6-di-tert-butylphenol, 4-undecyl-2,6-di-tert-butylphenol,4-dodecyl-2,6-di-tert-butylphenol, 4-tridecyl-2,6-di-tert-butylphenol,4-tetradecyl-2,6-di-tert-butylphenol,3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid butyl ester,3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid methyl ester,3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid 2-ethylhexyl esterand mixtures thereof.

In one embodiment the sterically hindered phenol is2,6-di-tert-butylphenol and mixtures thereof. In one embodiment thesterically hindered phenol is 4-(2-ethylhexyl)-2,6-di-tert-butylphenoland mixtures thereof. In one embodiment the sterically hindered phenolis 4-dodecyl-2,6-di-tert-butylphenol and mixtures thereof.

In one embodiment two sterically hindered phenols can be linked througha bridging group typically located at position 2- or 4- relative to thehydroxyl group. The bridging group can include —CH₂— (methylene bridge)or —CH₂OCH₂— (ether bridge) or mixtures thereof. Examples ofmethylene-bridged sterically hindered phenols include but are notlimited to 4,4′-methylenebis(6-tert-butyl-o-cresol),4,4′-methylenebis(2-tert-amyl-o-cresol),2,2′-methylenebis(4-methyl-6-tert-butylphenol),4,4′-methylene-bis(2,6-di-tertbutyl-phenol) and mixtures thereof.

Suitable examples of molybdenum dithiocarboamates include commercialmaterials sold under the trade names such as Vanlube 822™ and Molyvan™ Afrom R. T. Vanderbilt Co., Ltd., and Adeka Sakura-Lubem S-100 and S-165and S-600 from Asahi Denka Kogyo K. K.

Examples of suitable olefins that can be sulphurised include propylene,isobutylene, pentene, hexane, heptene, octane, nonene, decene, undecene,dodecene, undecyl, tridecene, tetradecene, pentadecene, hexadecene,heptadecene, octadecene, octadecenene, nonodecene, eicosene or mixturesthereof. In one embodiment, hexadecene, heptadecene, octadecene,octadecenene, nonodecene, eicosene or mixtures thereof and their dimers,trimers and tetramers are especially preferred olefins. Alternatively,the olefin can be a. Diels-Alder adduct of a diene such as 1,3-butadieneand an unsaturated ester such as butyl (meth) acrylate.

Another class of sulphurised olefins include fatty acids and theiresters. The fatty acids are often obtained from vegetable oil or animaloil; and typically contain 4 to 22 carbon atoms. Examples of suitablefatty acids and their esters include triglycerides, oleic acid, linoleicacid, palmitoleic acid or mixtures thereof. Often, the fatty acids areobtained from lard oil, tall oil, peanut oil, soybean oil, cottonseedoil, sunflower seed oil or mixtures thereof. In one embodiment fattyacids and mixed with olefins.

Corrosion Inhibitors

Corrosion inhibitors can include amine salts of carboxylic acids such asoctylamine octanoate, condensation products of dodecenyl succinic acidor anhydride and a fatty acid such as oleic acid with a polyamine, e.g.a polyalkylene polyamine such as triethylenetetramine, and half estersof alkenyl succinic acids in which the alkenyl radical contains 8 to 24carbon atoms with alcohols such as polyglycols.

Antiscuffing Agents

The lubricant may also contain an antiscuffing agent. Antiscuffingagents that decrease adhesive wear are often sulphur containingcompounds. Typically the sulphur containing compounds include organicsulphides and polysulphides, such as benzyldisulphide, bis-chlorobenzyl)disulphide, dibutyl tetrasulphide, di-tertiary butyl polysulphide,sulphurised sperm oil, sulphurised methyl ester of oleic acid,sulphurised alkylphenol, sulphurised dipentene, sulphurised terpene,sulphurised Diels-Alder adducts, alkyl sulphenyl N′N-dialkyldithiocarbamates, the reaction product of polyamines with polybasic acidesters, chlorobutyl esters of 2,3-dibromopropoxyisobutyric acid,acetoxymethyl esters of dialkyl dithiocarbamic acid and acyloxyalkylethers of xanthogenic acids and mixtures thereof.

Extreme Pressure Agents

Extreme Pressure (EP) agents that are soluble in the oil include sulphurand chlorosulphur-containing EP agents, chlorinated hydrocarbon EPagents, phosphorus EP agents, and mixtures thereof. Examples of such EPagents include chlorinated wax; organic sulphides and polysulphides suchas benzyldisulphide, bis-(chlorobenzyl) disulphide, dibutyltetrasulphide, sulphurised sperm oil, sulphurised methyl ester of oleicacid, sulphurised alkylphenol, sulphurised dipentene, sulphurisedterpene, and sulphurised Diels-Alder adducts; phosphosulphurisedhydrocarbons such as the reaction product of phosphorus sulphide withturpentine or methyl oleate; phosphorus esters such as the dihydrocarbonand trihydrocarbon phosphites, e.g., dibutyl phosphite, diheptylphosphite, dicyclohexyl phosphite, pentylphenyl phosphite;dipentylphenyl phosphite, tridecyl phosphite, distearyl phosphite andpolypropylene substituted phenol phosphite; metal thiocarbamates such aszinc dioctyldithiocarbamate and barium heptylphenol diacid; the zincsalts of a phosphorodithioic acid; amine salts of alkyl anddialkylphosphoric acids, including, for example, the amine salt of thereaction product of a dialkyldithiophosphoric acid with propylene oxide;and mixtures thereof.

Foam Inhibitors

Foam inhibitors are known and can include organic silicones such aspolyacetates, dimethyl silicone, polysiloxanes, polyacrylates ormixtures thereof. Examples of foam inhibitors include poly ethylacrylate, poly 2-ethylhexylacrylate and poly vinyl acetate.

Demulsifiers

Demulsifiers are known and include derivatives of propylene oxide,ethylene oxide, polyoxyalkylene alcohols, alkyl amines, amino alcohols,diamines and polyamines reacted sequentially with ethylene oxide orsubstituted ethylene oxides. Examples of demulsifiers include trialkylphosphates, polyethylene glycols, polyethylene oxides, polypropyleneoxides and (ethylene oxide-propylene oxide) polymers.

Pour Point Depressants

Pour point depressants are known and include esters of maleicanhydride-styrene copolymers, polymethacrylates; polyacrylates;polyacrylamides; condensation products of haloparaffin waxes andaromatic compounds; vinyl carboxylate polymers; and terpolymers ofdialkylfumarates, vinyl esters of fatty acids, ethylene-vinyl acetatecopolymers, alkyl phenol formaldehyde condensation resins, alkyl vinylethers and mixtures thereof.

Friction Modifiers

Friction modifiers other than a borate ester are known and can includefatty amines, esters, especially glycerol esters such as glycerolmonooleate, fatty phosphites, fatty acid amides, fatty epoxides,alkoxylated fatty amines, metal salts of fatty acids, sulfurizedolefins, fatty imidazolines, condensation products of carboxylic acidsand polyalkylene-polyamines, amine salts of alkylphosphoric acids.

Viscosity Modifiers

Viscosity modifiers are known and are typically polymeric materialsincluding styrene-butadiene rubbers, ethylene-propylene copolymers,polyisobutenes, hydrogenated styrene-isoprene polymers, hydrogenatedradical isoprene polymers, polymethacrylate acid esters, polyacrylateacid esters, polyalkyl styrenes, alkenyl aryl conjugated dienecopolymers, polyolefins, polyalkylmethacrylates, esters of maleicanhydride-styrene copolymers and mixtures thereof.

Some polymers can also be described as dispersant viscosity modifiers(often referred to as DVM) because they also exhibit dispersantproperties. Typically polymers of this type include polyolefins, forexample, ethylene-propylene copolymers that have been functionalizedwith the reaction product of maleic anhydride and an amine. Another typeof polymer is a polymethacrylate functionalised with an amine.

Seal Swelling Agents

Seal swelling agents are known and are typically esters or low viscositymineral oils with high naphthenic or aromatic content. Esters can bederived from monobasic and dibasic acids with monoalcohols, or esters ofpolyols with monobasic esters. Typically the alcohols contain 8 to 13carbon atoms. Suitable examples of mineral oil seal swelling agentsinclude adipates, azelates, and sebacates. Examples of suitable mineraloil seal swell agents include Exxon Necton-37 (FN 1380) and ExxonMineral Seal Oil (FN 3200).

Fluidity Modifiers

Fluidity modifier are known and can include Hydrocal-38 which is aproduct identified as a refined naphthenic oil, 40 Neutral naphthenicoil and a low molecular weight poly-α-olefin (Ethylflo™ 162).

INDUSTRIAL APPLICATION

The lubricated part of the present invention are useful in variouslubricants such as greases, gear oils, industrial fluids, hydraulicfluids, transmission fluids, turbine oils, circulating oils, fuel oilsand engine oils.

In one embodiment the lubricated part of the invention provides a methodfor lubricating an internal combustion engine, comprising supplyingthereto a lubricant comprising the composition as described herein. Theinvention is particularly suitable for diesel fuelled engines, gasolinefuelled engines, natural gas fuelled engine or a mixed gasoline/alcoholfuelled engine.

The use of the lubricated part of the invention can impart at least oneproperty selected from decreased wear, decreased filter plugging,decreased sludge formation, decreased phosphorus emissions, decreasedsulphur emissions, decreased sulphated ash formation and mixturesthereof.

The use of the lubricated part of the invention can decrease the totalsulphur content below about 0.5 wt %, preferably below about 0.3 wt %,even more preferably below about 0.2 wt % and more preferably belowabout 0.15 wt

The use of the lubricated part of the invention can decrease the totalphosphorus content below about 0.1 wt %, preferably, below about 0.085wt %, more preferably below about 0.06 wt %, even more preferably belowabout 0.055 wt % and even more preferably below about 0.05 wt %.

The use of the lubricated part of the invention can decrease thesulphated ash content below about 1.5 wt %, preferably below about 1.1wt %, more preferably below about 1.0 wt %, even more preferably belowabout 0.8 wt % and even more preferably below about 0.5 wt %.

The following examples provide an illustration of the invention. Theseexamples are non exhaustive and are not intended to limit the scope ofthe invention.

EXAMPLES

Lubricating Oil Composition A

A 15W-40 formulation is prepared containing about 15 percent of 100N APIGroup XX (ASK INVENTORS) base oil, about 4.05 mm2s-1 (cSt) at 100° C.and about 85 percent of 100N Group XX ASK INVENTORS) base oil, about 6.5mm²s⁻¹ (cSt) at 100° C. Additionally, about 6.8 wt % of a viscositymodifier (olefin copolymer), about 0.75 wt % of boron containingfriction modifier, about 4.0 wt % of a sterically hindered phenol of theantioxidant 3-(3,5-Di-tert-butyl-4-hydroxyphenyl)propionic acid butylester, about 10 wt % of polyisobutylene dispersant, about 100 ppm of acommercially available silicone antifoam agent are added to thelubricant formulation, about 2.1 wt % of magnesium phenate detergentincluding diluent oil, about 0.6 wt % of calcium sulphonate detergentincluding diluent oil and about 0.6 wt % polyisobutylene salixaratedetergent including diluent oil. The formulation is used to lubricatevalve train components with no coating.

Lubricating Oil Composition B

About 100 g of a 15W-40 formulation is prepared containing about 5percent of 600N API Group XX (ASK INVENTORS) base oil, about 12.2 mm2s⁻¹(cSt) at 100° C. and about 95 percent of 100N Group XX ASK INVENTORS)base oil, about 6.5 mm2s⁻¹ (cSt) at 100° C. Additionally, about 6.8 wt %of a viscosity modifier (olefin copolymer), about 0.2 wt % of maleicanhydride styrene copolymer viscosity index improver, about 1.3 wt % ofboron containing friction modifier, about 4.0 wt % of a stericallyhindered phenol antioxidant3-(3,5-Di-tert-butyl-4-hydroxyphenyl)propionic acid butyl ester, about10 wt % of polyisobutylene dispersant, about 100 ppm of a commerciallyavailable silicone antifoam agent are added to the lubricantformulation, about 2.1 wt % of magnesium phenate detergent includingdiluent oil, about 1.04 wt % of calcium dodecyl phenate sulphidedetergent and about 0.6 wt % of calcium sulphonate detergent includingdiluent oil. The formulation is used to lubricate valve train componentswith no coating.

Reference Example M

A lubricating oil composition A and used to lubricate valve traincomponents without a coating.

Reference Example N

A lubricating oil composition B and used to lubricate valve traincomponents without a coating.

Example 1

An oil of lubricating viscosity is prepared using the formulation of“Lubricating Oil Composition A” and used to lubricate valve traincomponents coated with a commercially available chromium nitride coating(Balinit®D) from Balzers Limited.

Example 2

An oil of lubricating viscosity is prepared using the formulation of“Lubricating Oil Composition A” and used to lubricate the rocker arm iscoated with a commercially available tungsten carbide coating(Balinit®C) from Balzers Limited.

Example 3

An oil of lubricating viscosity is prepared using the formulation of“Lubricating Oil Composition B” and used to lubricate the rocker arm iscoated with a commercially available chromium nitride coating(Balinit®D) from Balzers Limited.

Example 4

An oil of lubricating viscosity is prepared using the formulation of“Lubricating Oil Composition B” and used to lubricate valve traincomponents coated with a commercially available tungsten carbide coating(Balinit®C) from Balzers Limited.

Test 1 Cummins M11 Wear Test

Reference Examples 1 and 2 as well as Examples 1 to 4 are run in the APICH-4 Cummins M11 Engine test. This test uses a Cummins™ 370-E blockengine, which is an electronically governed in-line 6-cylinder 4-stroke,compression ignition engine. The test is conducted in two stages, thefirst about 65 hours and the second about 20 hours. During the firststage, the engine is over-fuelled and operated with retarded timing togenerate soot at an accelerated rate. During the second stage the engineis run at lower speed and higher torque, to induce wear. The crossheadwear, considered to be representative of valve train wear, is determinedand averaged for 12 crossheads. The valve adjuster wear is averaged for12 adjusters. Injector adjuster wear is averaged over six adjusters.Generally lower weight loss indicates better wear performance Theresults obtained are: Valve Adjuster weight Injector Adjuster weightExample loss (mg) loss (mg) Example Reference M 4.1 41.4 Example 1 7.339.3 Example 2 4.9 19.8 Example Reference N 13.5 42.6 Example 3 4.1 38.1Example 4 3.8 36.1Test 2 Sludge Test

The amount of sludge produced is measured by placing oil of lubricatingviscosity in an oil pan and rocker cover and left to stand for about 6hours at about 24° C. The sample is then placed at an angle of about 600from horizontal for about 8 hours at about 24° C. The amount of sludgeon the oil pan and rocker cover is in general those deposits that do notdrain off, but which can be removed by wiping. The grading scheme ratesthe deposits on the oil pan and rocker cover between 1 and 10, with 10being completely free of sludge. The results obtained are: ExampleSludge Rating Example Reference M 7.5 Example 1 7.7 Example 2 7.3Example Reference N 6.8 Example 3 7.1 Example 4 7.3Test 3 Filter Plugging

The test is carried out on the API CH-4 Cummins M11 Engine test and theCummins™ 370-E block engine. The test measures the difference inpressure between air leaving a filter at the start and end of the test.Generally the better results are obtained for examples with lowdifferences in filter pressure. The results obtained are: Difference inFilter Example Pressure (kPa) Example Reference M 25.3 Example 1 31.6Example 2 101.1 Example Reference N 74.8 Example 3 86.3 Example 4 13.6

Overall the examples indicate that the lubricating oils used incombination with a partial hard surface coating is capable of providingat least one property selected from decreased wear, decreased filterplugging, decreased sludge formation, decreased phosphorus emissions,decreased sulphur emissions, decreased sulphated ash formation andmixtures thereof.

While the invention has been explained, it is to be understood thatvarious modifications thereof will become apparent to those skilled inthe art upon reading the specification. Therefore, it is to beunderstood that the invention disclosed herein is intended to cover suchmodifications as fall within the scope of the appended claims.

1. A lubricated part comprising: (a) a part with at least a partial hardsurface coating of average thickness less than about 25 micrometres,said coating containing at least one moiety selected from the groupconsisting of silicides, nitrides, carbides, borides, oxides, sulphidesand mixtures thereof; (b) a detergent selected from at least one of thegroup consisting of a phenate salt, a sulphonate salt, a salixarate saltand mixtures thereof; and (c) an oil of lubricating viscosity.
 2. Thelubricated part of claim 1, wherein the partial hard surface coating hasan average thickness less than about 8 micrometres.
 3. The lubricatedpart of claim 1, wherein the partial hard surface coating contains atleast one moiety selected from the group consisting of nitrides,carbides and mixtures thereof.
 4. The lubricated part of claim 1,wherein the partial hard surface coating further comprises at least onemetal selected from the group consisting of Group IVb of the periodictable, Group Vb of the periodic table Group VIb of the periodic tableand mixtures thereof.
 5. The lubricated part of claim 4, wherein themetal is selected from the group consisting of chromium, tungsten,vanadium and combinations thereof.
 6. The lubricated part of claim 1,wherein the substrate of the sulphonate detergent is represented by theformula (R¹)_(k)-Z—SO₃M: wherein, each R¹ is independently a hydrocarbylgroup with a about 6 to about 40 carbon atoms Z is a cyclic or acyclichydrocarbon group; M is a valence of metal ion, hydrogen, ammonium ion,or mixtures thereof; and k is 1 to about
 5. 7. The lubricated part ofclaim 6, wherein the substrate of the sulphonate detergent incorporatesa metal ion selected from the group consisting of alkali metals,alkaline earth metals and mixtures thereof.
 8. The lubricated part ofclaim 1, wherein the substrate of the phenate detergent is representedby the formulae:

wherein the number of sulphur atoms in formula (VI) y, is in the rangefrom 1 to 8; the number of (CR¹⁰CR¹¹) moieties y, is in the range from 0to 8; hydrogen or hydrocarbyl groups; each R⁹ are independently hydrogenor a hydrocarbyl group; w, is in the range from 0 to 3, provided atleast one hydrocarbyl group is present on an oligomer; T is hydrogen oran (S)_(y) linkage terminating in hydrogen, an ion or a non-phenolichydrocarbyl group; and M is a valence of metal ion or hydrogen, x is aninteger and present in a sufficient number of times to form oligomers ofhydrocarbyl phenol; and R¹⁰ and R¹¹ are hydrogen or hydrocarbyl ormixtures thereof.
 9. The lubricated part of claim 1, wherein thesubstrate of the salixarate detergent is represented by a substantiallylinear compound comprising at least one unit of the formulae (I) or(II):

each end of the compound having a terminal group of formulae (III) or(IV):

such groups being linked by divalent bridging groups A, which may be thesame or different for each linkage; wherein in formulas (I)-(IV) R³ ishydrogen or a hydrocarbyl group; R² is hydroxyl or a hydrocarbyl groupand j is 0, 1, or 2; R⁶ is hydrogen, a hydrocarbyl group, or ahetero-substituted hydrocarbyl group; either R⁴ is hydroxyl and R⁵ andR⁷ are independently either hydrogen, a hydrocarbyl group, orhetero-substituted hydrocarbyl group, or else R⁵ and R⁷ are bothhydroxyl and R⁴ is hydrogen, a hydrocarbyl group, or ahetero-substituted hydrocarbyl group; provided that at least one of R⁴,R⁵, R⁶ and R⁷ is hydrocarbyl containing at least 8 carbon atoms; andwherein the molecules on average contain at least one of unit (I) or(III) and at least one of unit (II) or (IV) and the ratio of the totalnumber of units (I) and (III) to the total number of units of (II) and(IV) in the composition is about 0.1:1 to about 2:1.
 10. The lubricatedpart of claim 1, wherein the oil of lubricating viscosity is selectedfrom the group consisting of API Group II, III, or IV oil and mixturesthereof.
 11. The lubricated part of claim 1 further comprising a metalhydrocarbyl dithiophosphate represented by the formula:

wherein R¹² and R¹³ are independently hydrogen, hydrocarbyl groups ormixtures thereof, provided that at least one of R¹² and R¹³ is ahydrocarbyl group; M′ is a metal; and n is an integer equal to theavailable valence of M′.
 12. The lubricated part of claim 1 furthercomprising a borate ester prepared by the reaction of a boron compoundand at least one compound selected from epoxy compounds or equivalent,alcohols and mixtures thereof.
 13. The lubricated part of claim 1further comprising at least one other performance additives selectedfrom the group consisting of detergents other than those of component(b) of the invention, metal deactivators, dispersants, antioxidants,antiwear agents, corrosion inhibitors, antiscuffing agents, extremepressure agents, foam inhibitors, demulsifiers, friction modifiers otherthan a borate ester, viscosity modifiers, pour point depressants,fluidity modifiers and seal swelling agents.
 14. The lubricated part ofclaim 1 comprising: (a) a part with at least a partial hard surfacecoating of average thickness less than about 25 micrometres, saidcoating containing at least one moiety selected from the groupconsisting of silicides, nitrides, carbides, borides, oxides, sulphidesand mixtures thereof; (b) a detergent selected from at least one of thegroup consisting of a phenate salt, a sulphonate salt, a salixarate saltand mixtures thereof; and when present, each detergent is independentlypresent from about 0.05 to about 20 wt % of the lubricating oilcomposition; and (c) an oil of lubricating viscosity present from about5 to about 99.8 wt % of the lubricating oil composition; (d) a metalhydrocarbyl dithiophosphate present from about 0 to about 5 wt % of thelubricating oil composition; (e) a borate ester present from about 0 toabout 20 wt % of the lubricating oil composition; and (f) otherperformance additives present from about 0 to about 30 wt % of thelubricating oil composition.
 15. The lubricated part of claim 14,wherein the lubricating oil composition has a total sulphur contentbelow about 0.5 wt %; the total phosphorus content is below about 0.1 wt%; and the total sulphated ash content is below about 1.1 wt %.
 16. Thelubricated part of claim 1, wherein the partial hard surface coating isformed by at least one technique selected from the group consisting ofphysical vapour deposition, chemical vapour deposition, ion beamdeposition, ion beam enhanced deposition and plasma induced immersionprocess.
 17. The lubricated part of claim 16, wherein the technique usedto form the partial hard surface coating is physical vapour deposition.18. The lubricated part of claim 1, wherein the part is located in thevalve train, fuel injector train or mixtures thereof.
 19. The lubricatedpart of claim 18, wherein the part is selected from at least one of thegroup consisting of a rocker arm, a rocker arm pad, a cam follower, acam lobe, a crosshead, a valve adjuster, a injector adjuster andmixtures thereof.
 20. A lubricated part comprising: (a) a part with atleast a partial hard surface coating of average thickness less thanabout 25 micrometres, said coating containing at least one chromiummoiety selected from the group consisting of silicides, nitrides,carbides, borides, oxides, sulphides and mixtures thereof; (b) asalixarate salt detergent; and (c) an oil of lubricating viscosity. 21.A lubricated part comprising: (a) a part with at least a partial hardsurface coating of average thickness less than about 25 micrometres,said coating containing at least one tungsten moiety selected from thegroup consisting of silicides, nitrides, carbides, borides, oxides,sulphides and mixtures thereof; (b) a detergent package comprising: (i)a phenate salt; (ii) a sulphonate salt; and (c) an oil of lubricatingviscosity.
 22. A method for lubricating a part, wherein the lubricatedpart has at least one property selected from the group consisting ofdecreased wear, decreased filter plugging, decreased sludge formation,decreased phosphorus emissions, decreased sulphur emissions, decreasedsulphated ash formation and mixtures thereof; the method comprising alubricated part comprising: (a) a part with at least a partial hardsurface coating of average thickness less than about 25 micrometres,said coating containing at least one moiety selected from the groupconsisting of silicides, nitrides, carbides, borides, oxides, sulphidesand mixtures thereof; (b) a detergent selected from at least one of thegroup consisting of a phenate salt, a sulphonate salt, a salixarate saltand mixtures thereof; and (c) an oil of lubricating viscosity.